The present invention relates generally to a projection display, and more particularly to a projection display of the type that can project a viewing pupil having a limited area for the purpose of viewing a bright projected image.
The applicant has already filed patent applications concerning the inventions set forth in patent publications 1, 2, 3 or the like to come up with a 2D projection display, a 3D projection display, a projection display that enables a plurality of viewers to view separate projected images, or the like, each of which comprises a single or plural display devices, a single or plural projection optical systems including an aperture (exit pupil) for magnifying and projecting an image appearing on each display device, and a display panel comprising a Fresnel lens or Fresnel mirror located near images projected through such projection optical systems to form an aperture image of each projection optical system at a viewing pupil position and a diffuser plate or a hologram diffuser plate comprising a pit-and-projection diffusing surface having scatter action to magnify the aperture image of each projection optical system. Each one enables a viewer to view a bright projected image while the viewable pupil area is limited.
Patent Publication 1
JP(A) 2003-207743
Patent Publication 2
JP(A) 2004-102204
Patent Publication 3
JP(A) 2004-177920
With such projection displays designed to project the viewing pupil having a limited area, it is impossible to view any bright, normal projected image as the viewer's eyes are off that limited pupil area.
However, as long as one of both eyes of the viewer stays in the viewing pupil area especially in the horizontal direction, it is not necessarily easy for the viewer to take notice of another eye being off the limited pupil area.